From: Richard Purdie <rpurdie@rpsys.net> To: Jiri Kosina <jikos@jikos.cz> Cc: Henrique de Moraes Holschuh <hmh@hmh.eng.br>, linux-kernel@vger.kernel.org, FB-Dev <linux-fbdev-devel@lists.sourceforge.net> Subject: Re: 2.6.21-rc1 dims my LCD Date: Mon, 26 Feb 2007 15:43:37 +0000 [thread overview] Message-ID: <1172504617.5824.102.camel@localhost.localdomain> (raw) In-Reply-To: <Pine.LNX.4.64.0702261617240.10496@twin.jikos.cz> On Mon, 2007-02-26 at 16:24 +0100, Jiri Kosina wrote: > On Mon, 26 Feb 2007, Richard Purdie wrote: > > > Jiri: I've appended a patch that should already be queued, could you > > test and see if it solves the problem. > > Thanks. In the meantime I have gone through the code and I can confirm > that this is the root cause of what I am observing. > > Now regarding the patch - at the time when the dim happened previously, > currently there is a observable blink (after which the brightness is > correct). The reason for the behaviour is that its turning the backlight down/off to save power as it thinks the screen is blank. The blink therefore makes sense as far as the backlight class is concerned and its working as intended now. > I have put some debugging printk() into fb_notifier_callback(), > and it turns out that on FB_EVENT_CONBLANK, there are two successive calls > to backlight_update_status(), second immediately following the first one: > > Feb 26 15:11:14 thunder kernel: calling backlight_update_status() with bd->props.fb_blank == 1, bd->props.brightness == 0 > Feb 26 15:11:14 thunder kernel: calling backlight_update_status() with bd->props.fb_blank == 0, bd->props.brightness == 0 > > Is this really a right thing to do? This should come from two calls to fbcon_generic_blank() in drivers/video/console/fbcon.c with a different blank parameter and is therefore in a way outside the scope of the backlight class. It would be interesting to know why it decides to blank then immediately unblank the display though. I've cc'd the fbdev-devel list. Richard
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From: Richard Purdie <rpurdie@rpsys.net> To: Jiri Kosina <jikos@jikos.cz> Cc: FB-Dev <linux-fbdev-devel@lists.sourceforge.net>, linux-kernel@vger.kernel.org, Henrique de Moraes Holschuh <hmh@hmh.eng.br> Subject: Re: 2.6.21-rc1 dims my LCD Date: Mon, 26 Feb 2007 15:43:37 +0000 [thread overview] Message-ID: <1172504617.5824.102.camel@localhost.localdomain> (raw) In-Reply-To: <Pine.LNX.4.64.0702261617240.10496@twin.jikos.cz> On Mon, 2007-02-26 at 16:24 +0100, Jiri Kosina wrote: > On Mon, 26 Feb 2007, Richard Purdie wrote: > > > Jiri: I've appended a patch that should already be queued, could you > > test and see if it solves the problem. > > Thanks. In the meantime I have gone through the code and I can confirm > that this is the root cause of what I am observing. > > Now regarding the patch - at the time when the dim happened previously, > currently there is a observable blink (after which the brightness is > correct). The reason for the behaviour is that its turning the backlight down/off to save power as it thinks the screen is blank. The blink therefore makes sense as far as the backlight class is concerned and its working as intended now. > I have put some debugging printk() into fb_notifier_callback(), > and it turns out that on FB_EVENT_CONBLANK, there are two successive calls > to backlight_update_status(), second immediately following the first one: > > Feb 26 15:11:14 thunder kernel: calling backlight_update_status() with bd->props.fb_blank == 1, bd->props.brightness == 0 > Feb 26 15:11:14 thunder kernel: calling backlight_update_status() with bd->props.fb_blank == 0, bd->props.brightness == 0 > > Is this really a right thing to do? This should come from two calls to fbcon_generic_blank() in drivers/video/console/fbcon.c with a different blank parameter and is therefore in a way outside the scope of the backlight class. It would be interesting to know why it decides to blank then immediately unblank the display though. I've cc'd the fbdev-devel list. Richard ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
next prev parent reply other threads:[~2007-02-26 15:43 UTC|newest] Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top 2007-02-26 0:59 2.6.21-rc1 dims my LCD Jiri Kosina 2007-02-26 11:41 ` Richard Purdie 2007-02-26 12:35 ` Jiri Kosina 2007-02-26 14:21 ` Henrique de Moraes Holschuh 2007-02-26 14:49 ` Richard Purdie 2007-02-26 15:20 ` Henrique de Moraes Holschuh 2007-02-26 16:12 ` [PATCH] ACPI: ibm-acpi: improve backlight power handling Henrique de Moraes Holschuh 2007-02-26 16:38 ` Richard Purdie 2007-02-26 18:12 ` Henrique de Moraes Holschuh 2007-02-26 18:26 ` [PATCH] ACPI: ibm-acpi: improve backlight power handling (v2) Henrique de Moraes Holschuh 2007-02-26 21:25 ` Jiri Kosina 2007-02-26 21:42 ` Richard Purdie 2007-02-26 21:46 ` Henrique de Moraes Holschuh 2007-02-26 21:53 ` Richard Purdie 2007-02-26 17:21 ` [PATCH] ACPI: ibm-acpi: improve backlight power handling Jiri Kosina 2007-02-26 18:17 ` Henrique de Moraes Holschuh 2007-02-26 15:24 ` 2.6.21-rc1 dims my LCD Jiri Kosina 2007-02-26 15:43 ` Richard Purdie [this message] 2007-02-26 15:43 ` Richard Purdie 2007-02-26 17:13 ` [Linux-fbdev-devel] " Antonino A. Daplas 2007-02-26 17:13 ` Antonino A. Daplas 2007-02-26 16:03 ` Henrique de Moraes Holschuh 2007-02-26 17:01 ` Richard Purdie
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